I also tend to over-prep, my ratio is at least 1.5:1. But I do enjoy the prep.
I haven’t thought about it as a subgame… I would say the Mutant City Blues has a subgame in the character creation process. You need to follow a chart and there are disadvantages along the way. If you try to avoid them the character might not get the abilities you want them to have. (Yes, there is an optional rule to ignore the path system but I find it fun to use.)